In situ conversion of phenolic compounds as a tool to phenolic tolerance development by Saccharomyces cerevisiae

Depolymerization of lignin during pretreatment of lignocellulosic materials usually results in formation of several phenolic compounds. Phenolics are inhibitory to the growth and function of cells as biocatalysts in the production of second generation biofuels and chemicals from pretreated lignocellulosic biomass. Our research is focused on elucidating the metabolic pathways allowing Saccharomyces cerevisiae to metabolize phenolic compounds. We aim at understanding the conversion mechanisms of phenolic compounds in S. cerevisiae and harness them for metabolic engineering towards phenolic tolerant S. cerevisiae.

We have investigated the inhibitory action of thirteen phenolic compounds against S. cerevisiae. Our results showed that phenolic compounds have varied inhibition against S. cerevisiae and the cell response may be dependent on the structure of the compound involved. Under aerobic batch cultivation conditions, we have also studied the conversion of phenolic compounds by S. cerevisiae using coniferyl aldehyde, ferulic acid and p-coumaric acid as phenolic model compounds. We compiled a list of conversion products of the three compounds under investigation and we proposed a possible conversion pathway.

With our contribution, we present a proposed conversion pathway through which S. cerevisiae converts and detoxifies coniferyl aldehyde, ferulic acid and p-coumaric acid under aerobic cultivation condition.